functions take preference to assignin/evalin variables
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Can someone explain to me why the code below outputs 'test from function', indicating that the function takes preference to a variable assigned by assignin to the parent function scope? This just seems like a bug to me.......
function display_weirdness()
assign_weird();
disp(test)
end
function assign_weird
assignin('caller','test','test')
end
function t=test
t='test from function';
end
1 Comment
Stephen23
on 9 Jun 2020
Edited: Stephen23
on 9 Jun 2020
"...indicating that the function takes preference to a variable assigned by assignin to the parent function scope?"
Yes.
For good reason: because that is more efficient for the JIT engine. If the JIT engine always had to keep looking for magically created variables (e.g. that shadow functions, as your example does) and then when it finds them it would have to replace whatever it had already compiled with something entirely new and compile everything again, then clearly this would slow things down considerably.
This topic has been discussed plenty of times before:
Summary: passing data using the recommended methods is more efficient and less buggy than magically creating variables.
Accepted Answer
Ameer Hamza
on 9 Jun 2020
Edited: Ameer Hamza
on 9 Jun 2020
Yes, this is an inconsistent behavior similar to this question: https://www.mathworks.com/matlabcentral/answers/10727-bug-regarding-precedence-of-variables-over-functions-sharing-the-same-name, but it is not considered a bug, as explained by Walter's answer here: https://www.mathworks.com/matlabcentral/answers/10727-bug-regarding-precedence-of-variables-over-functions-sharing-the-same-name#answer_15521. It is a consequence of JIT. Following will work correctly
function display_weirdness()
test = '';
assign_weird();
disp(test)
end
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